Automatic door openers are common place in many types of commercial and industrial applications. For example, retail stores provide automatic door openers for customers entering and leaving with packages and or small children, and industrial businesses provide door openers for workers maneuvering forklift trucks between rooms and buildings closed off by doors and so on.
Typically, as a customer or worker approaches a door, a switch is engaged and the door opener is activated to open the door, held to the open position for a selected time period and then allowed or is initiated to close the door. A factor that needs to be considered in such a door opener design is safety. For example, if there is a power failure (such doors being operated by some form of power), there needs to be some provision that allows manual operation of the door. Other factors include appearance, appropriate interfit with conventional doors and door support structures and cost.
An example of a door opener that satisfies each of the criteria expressed above is the commonly owned U.S. Pat. No. 4,356,442. This patent discloses a pneumatic operated door opener that provides a pushing element at the end of a lever that engages one side of the door, the lever being connected to a pneumatic motor that is actuated by remote control. When actuated, the lever supplies force to the side of the door to push the door open. A separate door closer acting on the opposite side of the door closes the door upon release of the pneumatic power. This door opener has the advantage of being easily mounted without concern for perfect alignment of pivotal axes as between the door and the opener, it is low cost and it provides no resistance to manual opening of the door.
The present invention is believed to provide improvements over this door opener in that it eliminates the separate door closer while retaining the ability to manually open and close the door. Other advantages will be disclosed and/or apparent from the following disclosures.